1. Field of the Invention
The present invention relates to a device for generating various mode vibrations, and more particularly, to a device for generating various mode vibrations by stacking and modularizing two or more vibration generators whose vibration directions, amounts or frequencies are different from one another.
2. Description of the Related Art
In general, one of essential functions of a communication terminal is an incoming call notification function. For functions frequently used as this incoming call notification function, there are a function of generating sounds such as a melody or a bell and a function of vibrating the terminal.
Specifically, the vibrating function is mainly used in order not to cause harm to others owing to a melody or a bell generated from a speaker of the terminal. This vibration of the terminal can be usually generated through a driving force generated by a small-sized vibration motor of the terminal and then transmitted to the terminal's case.
In the meanwhile, the necessity for a multi-mode vibration generator has been recently increased for embodying multi-functions of the terminal, especially a multimedia function.
Rotation-type vibration motors currently adopted in the terminal are classified into a coin-type vibration motor of thin thickness and a bar-type vibration motor of long type, according to their shape.
FIG. 1A is an exploded view of a conventional coin-type vibration motor, and FIGS. 1B and 1C is a sectional view of a conventional coin-type vibration motor. Reference will now be made to FIGS. 1A to 1C.
Referring to FIGS. 1A to 1C, a conventional coin-type vibration motor 100 includes a stator assembly 110 and a rotor assembly 120.
The stator assembly 110 is constructed to include a bracket 111 of a circular plate, a lower substrate 112 attached to the center of an upper surface of the bracket 111, and a ring-type magnet 113 attached around the lower substrate 112 and on the upper surface of the bracket 111.
The upper part of the bracket 111 is covered by a case 150, and the bracket 111 and the case are connected by a center shaft 130.
The rotor assembly 120 is rotatably connected to the shaft 130. The rotor assembly 120 includes a bearing 121, a coil assembly 122, a counter weight 123, a commutator 124, an upper substrate 125 and an insulator 126. Here, the rotor assembly 120 becomes eccentric by the counter weight 123.
Here, the lower parts of the stator assembly 110 and the rotor assembly 120 are fixed to the lower substrate 112. The upper parts of the stator assembly 110 and the rotor assembly 120 are electrically connected by a brush 140 configured to contact with the commutator 124.
The lower substrate 112 and an electric source are connected by a lead line 114 shown in FIG. 1A. Also, the lower substrate 112 and an electric source may be connected by a connector or an FPCB (flexible printed circuit board) connection port instead of the lead line 114.
In FIG. 1C, non-described reference numbers 117, 118, 119 and 127 respectively represent a mold part, a yoke, an auxiliary plate and a washer.
Reference will now be made to an operation of the conventional coin-type vibration motor 100.
Referring to FIG. 1A, an outer electric power is applied through the lead line 114, a current then flows through the brush 140 and the upper substrate 125 into the coil assembly 122 located in the eccentric rotor assembly 120. Thereafter, by an interaction of a field formed by the magnet 113 and the case 150, the eccentric rotor assembly 120 rotates around the shaft 130 with the bearing 121 intervening therebetween, thereby inducing a vibration.
Here, a vibration direction of the coin-type vibration motor 100 corresponds to a rotation plane of the rotor assembly 120, namely a plane perpendicular to the shaft 130.
FIG. 2 is a sectional view showing a side of a conventional bar-type vibration motor.
Referring to FIG. 2, a bar-type vibration motor 200 includes a stator assembly 210 and a rotor assembly 220.
The stator assembly 210 includes a body 211, a cap 212 fixed to a part of the body 211, and a magnet 213. The body 211 is hollow cylinder shaped, and the magnet 213 is fixed to an inside of the body 211.
The rotor assembly 220 includes an eccentric weight 223, a plurality of commutators 224 fixed to a side of a fixed frame 225 and spaced apart from one another, and a plurality of core assemblies 222 fixed to the fixed frame 225.
In the fixed cap 212, a pair of brushes 240 are attached to a fixed substrate (not shown). The brushes 240 are connected to a lead line 215 for supplying an electric power, and applies a current to the commutators 224.
Here, a vibration direction of the bar-type vibration motor 200 corresponds to a rotation plane of the rotor assembly 220.
Although the above-stated coin-type/bar-type vibration motors are somewhat different from each other in their shape, both the motors are similar in that they obtains a mechanical vibration by rotating a rotator assembly having unbalanced mass and generates a rotation force by applying a current to a rotor coil through a contact point between a brush and a commutator.
However, in case of a rotation-type vibration motor which generates a vibration by rotating an eccentric rotator assembly as stated above, since an eccentric amount, an eccentric mass and a driving rpm (revolutions per minute) are predetermined during the motor design stage, whereby a vibration amount (i.e. a vibration force) is fixed, the size of a vibration generated by the motor is constant.
That is, since a vibration force (F) is proportional to mass of a vibrating body (m), an eccentric amount (e), the square of a driving rpm (ω2) as shown in the following Equation (1) and their values are predetermined during the motor design stage, only a vibration of constant amount is generated by the motor.F∝m×e×ω2  (Equation 1)
Also, a vibration direction of the coin-type or the bar-type vibration motor is confined to a rotation plane of a rotor assembly, whereby only a vibration of single shape is generated. Therefore, the coin-type or the bar-type vibration motor cannot be adopted in a multimedia-functioned communication terminal that requires various patterned vibrations to be generated. Besides, in case of the coin-type or the bar-type vibration motor, users cannot freely select the amounts of a vibration.
FIG. 3 illustrates a conventional horizontal direction linear vibrator generating a horizontally linear vibration. Reference will now be made to a structure and operation of a conventional linear vibrator 300.
Referring to FIG. 3, a pair of brackets 314 and 315 are attached to axial outer ends of a cylinder-shaped frame 310 and supports both ends of a fixed axis. A cylinder-shaped coil 320 having a power input port is attached on an inner peripheral surface of the cylinder-shaped frame 310.
A moving part 350 includes a cylinder-shaped and radially-magnetized magnet 330, bearings 317 and 318 connected to axial ends of the magnet 330, and an elastic part 340 placed between the bearings 317 and 318 and the brackets 314 and 315.
FIG. 4 is a sectional view of a conventional vertical direction linear vibrator generating a vertically linear vibration. Reference will now be made to a structure and operation of a conventional vertical direction linear vibrator 400.
In the vertical direction linear vibrator 400 shown in FIG. 4, by an interaction between a magnetic force generated from a magnet and an electromagnetic force of a given frequency generated form a coil assembly, a moving part resonates vertically, thereby inducing a vertical vibration. The vertical direction linear vibrator 400 includes a case 410, a moving part 420 and a coil assembly 441.
The moving part 420 includes a magnet 421, a yoke 422 surrounding the magnet 421, a mass body 423 of a given mass attached to both sides of the yoke 422, and a plate 424.
The coil assembly 441 is placed to an upper side of the moving part 420, and generates an electromagnetic force of a given frequency.
An elastic part 430 is connected to the moving part 420 and induces a vibration when a frequency is applied.
In this type of the vertical direction linear vibrator 400, the coil assembly 441 may be attached to a lower part. In this case, a flexible printed circuit may be placed to a lower side of the coil assembly 441 so that the flexible circuit is connected to an input port.
In the linear vibrator shown in the FIGS. 3 and 4, by an interaction between a magnetic force generated from the magnet 330 or 421 and an electromagnetic force of a given frequency generated form the coil assembly 320 or 441, the moving part 350 or 420 resonates horizontally or vertically, thereby inducing a horizontal or vertical vibration.
In the linear vibrator using a resonant frequency, a vibration force (F) is proportional to mass of a vibrating body (M), displacement of the vibrating body (X), the square of a resonant frequency (f2) as shown in the following Equation (2).F∝M×X×f2  (Equation 2)
However, this linear vibrator also cannot generate various vibrations other than a vibration of predetermined direction. In addition, although the linear vibrator can adjust its vibration amount by changing a resonant frequency according to an applied voltage, it can basically generate only a vibration of a given amount predetermined during its design stage.
Therefore, a vibration generator capable of generating various vibrations has been required in the related art.
In addition, the necessity for a modularized vibration generator, which can be reflow attached without changing its attachment area and the number of assembling processes and can generate various mode vibrations in respect of a vibration direction, a vibration frequency and/or a vibration amount, has be recently increased.